Antibacterials Flashcards
Prophylaxis for rheumatic fever
Phenoxymethylpenicillin or sulfadiazine.
Invasive group A streptococcal infection: prevention of secondary cases
Phenoxymethylpenicillin.
Patients who are penicillin allergic, either azithromycin [unlicensed use] or clarithromycin [unlicensed use] or erythromycin (in pregnancy or within 28 days of giving birth).
Meningococcal meningitis: prevention of secondary cases
Ciprofloxacin or rifampicin or i/m ceftriaxone [unlicensed indication].
Haemophilus influenzae type b infection: prevention of secondary disease
Rifampicin;
Alternative if rifampicin unsuitable: ceftriaxone [unlicensed] (based on limited evidence), or oral ciprofloxacin [unlicensed] or azithromycin [unlicensed] (however effectiveness in healthy individuals has not been determined).
Diphtheria: prevention of secondary cases
Azithromycin or clarithromycin;
Alternative if more easily administered: intramuscular benzylpenicillin sodium.
Pertussis, antibacterial prophylaxis
Clarithromycin (or azithromycin or erythromycin).
Pneumococcal infection in asplenia or in patients with sickle-cell disease, antibacterial prophylaxis
Phenoxymethylpenicillin.
If penicillin-allergic, erythromycin.
Orthopaedic surgery, antibacterial prophylaxis
- Joint replacement including hip and knee
Single dose of i/v cefuroxime alone
or i/v flucloxacillin + i/v gentamicin
Orthopaedic surgery, antibacterial prophylaxis
- Closed fractures
Single dose of i/v cefuroxime or i/v flucloxacillin
Orthopaedic surgery, antibacterial prophylaxis
- Open fractures
Use i/v co-amoxiclav alone or
i/v cefuroxime + i/v metronidazole
PROM prevention of intra-uterine infection
Erythromycin.
Penicillins MOA
Beta-lactam antibiotics that inhibit bacterial cell wall synthesis
prevents cross linking of peptidoglycans
Why can flucloxacillin by used in infections caused by beta lactamase producing bacteria?
Beta-lactamase stable
When is benzylpenicilin commonly used
Prehospital in meningococcal disease
When is Pen V (phenoxymethylpenicillin) commonly used / 1st line
Streptococcal tonsilitis
When is flucloxacillin commonly used / 1st line?
Impetigo
Cellulitis
Mastitis
Osteomyelitis
Septic arthritis
When is Amoxicillin commonly used / 1st line?
CAP (low - mod severity)
Exacerbations of chronic bronchitis
Acute otitis media
Acute sinusitis
Oral infections
Cephalosporins MOA
Broad spectrum beta-latam antibiotics
Attach to penicillin binding proteins to interrupt cell wall synthesis
Cefalexin usually taken via?
Mouth
Cephalosporins
1st gen
2nd gen
3rd gen
Cefalexin
Cefuroxime
Cefotaxime and ceftriaxone
Tetracyclines MOA
Inhibit protein synthesis
Which tetracycline may be used in malaria prophylaxis?
Doxycycline
Tetracyclines are tx of choice for which conditions?
Chlamydia
Lyme disease
MOA of aminoglycosides
Interfere with bacterial protein synthesis
When is gentamicin contraindicated
Myasthenia gravis
Gentamicin monitoring
Take peak (1hr after dose) and trough (pre next dose)
If trough is high, increase interval between doses
If peak is high, decrease the dose
Macrolides MOA
Inhibit protein synthesis
Main use for fusidic acid
Primarily topically for minor staphylococcal skin / eye infection
Max length of fusidic acid course length
10 days
Why is chloramphenicol rarely used systemically?
Serious adverse effects
Aplastic anaemia
Peripheral neuropathy
Optic neuritis
For how long after healing should chloramphenicol be used to tx bacterial eye infections?
48HRS
MOA of vancoymycin
Glycopeptide abx, inhibits peptidoglycan formation
Therefore acts against GRAM +VE
(anaerobic and aerobic)
Cautions for vancomycin
Hx of deafness
Caution in the elderly
When is vancomycin given orally?
C. diff colitis
MOA of metronidazole
Bacterial nucleic acid synthesis inhibitor
High activity against anaerobic and protozoa
Co-trimoxazole =
Trimethoprim and sulfamethoxazole
Contraindication for trimethoprim
Any blood disorder (dyscrasis)
If trimethoprim is used during pregnancy what should be px alongside it?
5mg folic acid daily
